The preparation of thermoset cycloolefin polymers such as dicyclopentadiene (DCPD) using metathesis catalysts is described in Klosiewicz, U.S. Pat. Nos. 4,400,340 and 4,520,181. A two-stream reaction injection molding process is used in which a first stream, including the catalyst, and a second stream, including a catalyst activator, are combined in a mix head and immediately injected into a mold where polymerization and molding take place simultaneously.
The preferred catalyst component as taught by Klosiewicz is a tungsten halide, and preferably a mixture or complex of tungsten hexachloride (WCl.sub.6) and tungsten oxytetrachloride (WOCl.sub.4). The tungsten compound is not normally soluble in the cycloolefin, but can be solubilized by complexing it with a phenolic compound such as a phenol, alkyl phenol, halogenated phenol or phenolic salt.
U.S. Pat. No. 4,981,931 describes another metathesis catalyst system in which a tungsten halide catalyst having the formula WX.sub.n (OR).sub.6-n is used, where X is Cl or Br, n is 2 or 3 and R is a phenoxy group that can be substituted by Cl, a phenyl, 1-8 carbon alkoxy or 1-9 carbon alkyl group. Another tungsten halide catalyst is described in U.S. Pat. No. 5,082,909 and has the formula WOCl.sub.4-x (OAr).sub.x, where Ar is a hindered phenyl ring and x is 1-3. These catalysts are both used in conjunction with a triphenyltin hydride or a trialkyltin hydride as an activator. U.S. Pat. No. 4,882,401 discloses the use of molybdenum or tungsten halide catalysts in combination with dialkylzinc compounds, alkylzinc halides or aromatic zinc compounds as activators.
In order to prevent premature ionic polymerization of the DCPD monomer in which the catalyst is typically dissolved, the catalyst component can be stabilized by reacting it with a chelating agent or Lewis base. Stabilizer compounds include, for example, diethyl ether, ethylene glycol dimethyl ether (glyme), bis(methoxy)ethyl ether (diglyme), benzonitrile, acetonitrile, and tetrahydrofuran. The stabilizers are not necessary when storage times are short.
The metathesis catalyst is typically activated with an alkylating agent such as, for example, an aluminum alkyl, alkyl tin hydride, magnesium dialkyl, lead alkyl or a silane. Once the catalyst is alkylated, it forms the active species, a tungsten or molybdenum carbene (alkylidene) compound.
Takagi et al. described the use of unsolvated Grignard reagents as activators for the metathesis of acyclic olefins in T. J. Oil Chem. Soc. Japan 1975, 24 (8), 518. No polymers were formed. The mechanism for the activation of the catalyst for the metathesis of acyclic olefins was described in J. Levisalles et al., J. Organomet. Chem. 1980, 192, 375. P. A. Raven and E. J. Wharton demonstrated that a mixture of WCl.sub.6 in benzene and an ethereal Grignard reagent such as n-propylmagnesium bromide is active in disproportionating olefins (Chemistry and Industry, Apr. 1, 1972, 292). However, none of these references has disclosed the use of an ethereal Grignard reagent for activating the ring-opening metathesis of polycyclic polyolefins.